1. Field of the Invention
The present invention relates to a magnet coupling for transmitting rotating force by magnetic force thereof.
2. Related Arts
A typical magnet coupling shown in FIG. 3 is composed of a pair of disk like permanent magnets 13, 16 disposed between a driving shaft 21 such as a motor shaft and a load side driven shaft 31, and defining a gap .delta. (herebelow referred to as a magnetic gap) therebetween.
The magnet coupling transmits rotating force from the driving shaft 21 to the driven shaft 31. At that time, the magnitude of the rotating force is significantly affected by variation in dimension of the magnetic gap .delta.. Specifically, the rotating force is transmitted from the driving shaft 21 to the driven shaft 31 by attracting force of the magnet coupling, and the magnitude of the rotating force transmitted to the driven shaft 31 is approximately proportional to the magnitude of the attracting force. Therefore, the magnitude of the rotating force transmitted to the driven shaft 31 is inversely proportional to the square of the dimension of the magnetic gap .delta..
Because of this, it is necessary for the magnetic gap .delta. to be precisely set. This requires sufficiently reducing variations in assembling of parts forming the magnetic couple in addition to sufficiently reducing variations in dimensions of the parts, resulting in increase in manufacturing cost of the magnet coupling. This kind of problem is caused not only to the magnet coupling using the permanent magnets, but to other types of couplings such as an eddy current coupling using an electromagnet.